The design and structure of solid state micrologic elements is described. In discussing these elements, the emphasis is placed on the use of multiple diffusion, masking and evaporation in the fabrication of integrated microcircuits in a single piece of silicon. It is shown that both active and passive elements can be built into the silicon substrate and that electrical isolation of the individual components can be achieved when necessary. The techniques employed in making the interconnection will be described. Microphotographs and cross sectional views of these elements at various stages of construction are shown in conjunction with a discussion of the following process steps: 1. Materials preparation. 2. The seven masking operations. 3. Electrical isolation of active and passive elements within the silicon substrate. 4. Diffusion of active and passive elements. 5. Surface passivation. 6. Electrical interconnection of components. 7. Packaging and testing. Economy, reliability and design flexibility are some of the more important considerations of this approach. These are reviewed in connection with the present family of six micrologic elements. The feasibility of extending present technology to the development and manufacture of differing and more complex microcircuits and subsystems is discussed.